Enchondroma (en-kon-DRO-ma) is a type of benign (noncancerous) tumor that begins in
the cartilage found inside the bones. Enchondromas rarely cause pain or other symptoms,
so most remain undiagnosed until x-rays are taken for an unrelated injury or condition.

In the majority of cases, enchondromas do not require treatment. In rare cases, however,
multiple tumors may weaken the bone, causing it to fracture. When this occurs, surgery
may be needed to remove the tumor and prevent additional fractures.

Description

Enchondromas can occur in anyone but are most common in patients between 10 and 20
years old. They are most often found in the small bones of the hand. In fact, enchondroma
is the most common tumor in the hand. Enchondomas can also develop in the body's long
bones, such as the femur (thighbone), tibia (shinbone), and humerus (upper arm bone).

Enchondromas are most often solitary tumors. In rare cases, however, multiple tumors
can appear as part of a condition such as Ollier's disease or Maffucci's syndrome.

Single enchondromas rarely become cancerous, though the chances are a little higher
in patients with Ollier's disease and Maffucci's syndrome. When enchonromas do become
cancerous, they usually become a type of malignant cartilage tumor called a chondrosarcoma.

Distinguishing between a noncancerous enchondroma and the very low-grade form of a
cancerous tumor can be difficult, even for orthopaedic tumor surgeons.

In most cases, enchondromas are not painful and do not cause any symptoms. However,
if the tumors appear in the hands or feet, or if there are multiple lesions, the bone
can weaken and become deformed. This can lead to pathologic bone fractures and enlargement
of the affected fingers.

In patients with Ollier's disease and Maffucci's syndrome, bone deformities can be
quite severe. If pain from other sources has been excluded, your doctor will carefully
study the tumor to determine whether it could actually be a low-grade chondrosarcoma.
Pain at night or at rest is more likely to indicate a malignant tumor. However, because
pain is a common symptom of many conditions and injuries, your doctor will conduct
a thorough evaluation.

Because they do not often cause symptoms, most enchondromas are found when routine
x-rays are taken for another reason such as an injury or arthritis. When this occurs,
your doctor will conduct an examination and order a number of tests to confirm that
your tumor is actually an enchondroma—and not a more aggressive or cancerous tumor.

Physical Examination

During the exam, your doctor will take a complete medical history and ask about your
symptoms. He or she will ask if your tumor is painful and when the pain occurs. There
is greater concern if the pain occurs when you are at rest or at night and does not
go away. Pain caused by activity is less worrisome.

In some cases, your doctor may give you an injection into the joint near the tumor.
If the injection relieves your pain, it indicates that the enchondroma is not the
cause.

Tests

X-rays. X-rays provide images of dense structures such as bone. On x-rays, enchondromas appear
as small (less than 5 cm), lobe-shaped, darkened tumors in the middle of the bone.
They usually contain white spots or calcification within. The white areas of the tumor
show a pattern of rings and arcs that indicates the tumor contains cartilage.

X-rays, taken from the front (left) and side (right) show a benign enchondroma. The tumor was discovered when x-rays were done after
a knee injury.

An x-ray (left) and MRI scan (right) showing a large enchondroma of the fifth metacarpal of the hand.

Other imaging studies. Your doctor may order a computerized tomography (CT) or magnetic resonance imaging
(MRI) scan to help further evaluate your tumor. These scans give a more complete picture
of the bone around the tumor. If the tumor has turned into a malignancy, the scans
may show bone erosion, bone inflammation, or a mass growing outside the bone.

In some cases, your doctor may order a bone scan. During this test, a very small amount
of radioactive dye is injected into the body intravenously. Both benign and malignant
tumors can cause an increased uptake of the radioactive material in the bone due to
bone activity. Enchondromas are typically active on bone scans.

Bone scan shows an uptake of radioactive dye near the end of the thigh bone.

Biopsy. A biopsy may be necessary to confirm the diagnosis of enchondroma. In a biopsy, a
tissue sample of the tumor is taken and examined under a microscope.

A biopsy can be performed under local anaesthesia with a needle or as a small open
operation.

Grading. The grade, or aggressiveness, of the tumor is determined by imaging studies and how
the tumor looks under a microscope.

Under the microscope, enchondromas have islands of cartilage that are easy to tell
apart from the normal bone that surrounds them. Usually, cartilage is not found in
the center of bones. Enchondromas in the hand and foot or in patients with Ollier's
disease or Maffucci's syndrome may contain more odd-looking cartilage. It may be difficult
to distinguish these tumors from low-grade chondrosarcomas.

Low-grade chondrosarcomas look more cellular than enchondromas under a microscope
and there is less normal bone in the tumor. Because low-grade chondrosarcomas and
enchondromas look similar, experienced surgeons, radiologists, and pathologists will
work together to get the best interpretation of the tumor.

Characteristics of a more aggressive tumor or a malignant chondrosarcoma include:

Most enchondromas require no treatment at all. When treatment is needed, the specific
type of treatment is sometimes the subject of debate among doctors. This is because
it is difficult to determine the aggressiveness of the lesion.

Nonsurgical Treatment

If your tumor does not cause symptoms, your doctor may recommend observation and monitoring
to see if it grows. During this time, you may need periodic x-rays or other tests.
Most doctors think that tumors without symptoms do not need to be removed.

Surgical Treatment

Curettage

Curettage is the surgical procedure most commonly used to treat enchondromas. In curettage,
the tumor is scraped out of the bone. Once enchondromas are removed, most will not
return. If a tumor has caused your bone to fracture, your doctor will usually allow
the fracture to heal before treating the tumor. The tumor will then be curetted out
to prevent another fracture.

Bone Graft

After curettage, your doctor may fill the cavity with a bone graft to stabilize the
bone. A bone graft is bone taken from a donor (allograft) or from another bone in
your body (autograft). In some cases, another substance may be used to fill the cavity.

Some tumors may look like simple enchondromas on x-ray—but are painful. Treatment
of these lesions can be controversial. Some doctors recommend surgical curettage.
Others think that the tumors are not likely to be the cause of the pain in the area—so
they recommend monitoring with regular x-rays.

Unfortunately, biopsies are not often helpful in these cases. Even for specialized
bone pathologists, it can be difficult to differentiate between a benign enchondroma
and a low-grade chondrosarcoma. In this setting, needle biopsies are not recommended.

More aggressive tumors with bone destruction or with a mass growing outside the bone
are usually chondrosarcomas. These malignant tumors need to be removed in their entirety.
The specific procedure used depends upon the grade of the tumor.

There is a great deal of ongoing research on enchondromas and chondrosarcomas. Current
studies are trying to identify chemical markers that may help doctors tell the difference
between benign and malignant cartilage tumors.

Other studies are looking at the different characteristics of tumors on specialized
imaging studies such as MRI, CT, or PET (positron emission tomography) scans.

AAOS does not endorse any treatments, procedures, products, or physicians referenced
herein. This information is provided as an educational service and is not intended
to serve as medical advice. Anyone seeking specific orthopaedic advice or assistance
should consult his or her orthopaedic surgeon, or locate one in your area through
the AAOS "Find an Orthopaedist" program on this website.